From a1f98849fdf2f2fef3ef1c260178cd5fc662b773 Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Sun, 8 Mar 2009 22:34:45 -0400 Subject: [ARM] allow for alternative __copy_to_user/__clear_user implementations This allows for optional alternative implementations of __copy_to_user and __clear_user, with a possible runtime fallback to the standard version when the alternative provides no gain over that standard version. This is done by making the standard __copy_to_user into a weak alias for the symbol __copy_to_user_std. Same thing for __clear_user. Those two functions are particularly good candidates to have alternative implementations for, since they rely on the STRT instruction which has lower performances than STM instructions on some CPU cores such as the ARM1176 and Marvell Feroceon. Signed-off-by: Nicolas Pitre --- arch/arm/include/asm/uaccess.h | 2 ++ arch/arm/lib/clear_user.S | 3 ++- arch/arm/lib/copy_to_user.S | 3 ++- 3 files changed, 6 insertions(+), 2 deletions(-) (limited to 'arch/arm') diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 7897464e0c2..0da9bc9b3b1 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -386,7 +386,9 @@ do { \ #ifdef CONFIG_MMU extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n); extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n); +extern unsigned long __must_check __copy_to_user_std(void __user *to, const void *from, unsigned long n); extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); +extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned long n); #else #define __copy_from_user(to,from,n) (memcpy(to, (void __force *)from, n), 0) #define __copy_to_user(to,from,n) (memcpy((void __force *)to, from, n), 0) diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S index 4d6bc71231f..844f56785eb 100644 --- a/arch/arm/lib/clear_user.S +++ b/arch/arm/lib/clear_user.S @@ -18,7 +18,8 @@ * : sz - number of bytes to clear * Returns : number of bytes NOT cleared */ -ENTRY(__clear_user) +ENTRY(__clear_user_std) +WEAK(__clear_user) stmfd sp!, {r1, lr} mov r2, #0 cmp r1, #4 diff --git a/arch/arm/lib/copy_to_user.S b/arch/arm/lib/copy_to_user.S index 22f968bbdff..878820f0a32 100644 --- a/arch/arm/lib/copy_to_user.S +++ b/arch/arm/lib/copy_to_user.S @@ -86,7 +86,8 @@ .text -ENTRY(__copy_to_user) +ENTRY(__copy_to_user_std) +WEAK(__copy_to_user) #include "copy_template.S" -- cgit v1.2.3-70-g09d2